# Thread: C & Z Feed rate

1. ## C & Z Feed rate

How do you calculate the C & Z Feed rate Both Axis moving at the same time, I have tried but can never figure it out so I guess at it

Randy

2. Since C axis is a little uncommon, I'm first going to ask what axis it is.

We have 1 milling machine with C axis (X Y Z B C). It is a rotary head machine, the head can turn 360degrees 27 times(9999.999degrees) before the software on the controller won't handle any more. Since it is positioned in degrees, the feedrate needs to be in 'inverse time'.

If yours is similar, do a google search for "inverse time feedrate calculation" (without the ""). Click the first page listed (actually a .pdf document). Scroll down to page 8. It gives an example with and formula(s).

3. What control / application?
Feedrates for C/Z moves vary from one control to the next.
Some apply the feedrate to the Z-axis move, and let the C-axis fend for itself.
Others, like Dustin mentioned, will do a degrees per minute type of feedrate, And I've even had the "pleasure" of working with a control that would allow you to program a normal IPR/IPM feedrate for the C axis, and the Z-axis move would get to the endpoint at the right time, but you may have buried the tool!

4. The feedrate calculation will have to be based on the distance away from the centerline of the C axis. 5" from centerline and moving 360 degrees per minute yields 31.4 IPM. If movement on Z axis causes movement toward or away from centerline the feedrate will increase or decrease as the position changes.

5. G'day
Mate, I'm waiting for you to answer what sort of machine it is but you dont seem very interested in having the right answer. If it is a lathe fitted whith C Axis I can help.
John

6. Yes, Im Sorry it's a Lathe with fanuc 18T Control Hitachi seiki super Hicell 250 with XYZC and B axis

7. G'day
Good that you got back. I'm assumming the C axis is the rotary axis. Is it not?
I'll scan the pages with the calculations from my "bible" and post them to you. Just wait a litlle, but I have it. Last night I was up till 10 past 5 AM. sending posts to forums. My way of enjoying life in retirement.
John

8. G'day again
Here are the files on cutting speeds and feed calculations for C/Rotary axis. Open attachment.
John